This invention relates to a method for electronically reproducing an original picture for the fabrication of a printing plate by exposing the original picture and recording its reproduction on the basis of picture signals obtained by photoelectronic scanning of the original picture, in which where the original picture contains picture pattern regions of continuous tone ranging from a high density to a low density in combination with line picture regions such as character regions, picture pattern regions having gradation are output as halftone picture images and on the other hand, line picture regions are output as high-resolution line picture images faithful to the line picture regions in the original picture or if necessary, as halftone images having the same percentage of dot areas, namely, as tint images.
Coupled with popularization of the color photomechanical process in recent years, there is a standing desire for an improvement to the productivity by plate-making color scanners in order to reproduce a number of color images efficiently as color-separated halftone images.
In a final image to be output generally, there are picture pattern images having continuous gradation in combination with line picture images such as characters and/or graphics.
Plate-making color scanners, which are generally called direct scanners and are adapted to perform color separation and at the same time to record reproduced images as halftone images, are accompanied by such a problem that the resolution of areas containing line pictures is deteriorated when fabricating color-separated plates with an original picture for a complete block copy in which original line pictures such as characters, graphics and/or line drawings and original picture patterns having continuous gradation such as color pictures and/or picture patterns have been laid out in a suitable pattern, because the line pictures are also reproduced as halftone patterns.
The present applicant has already filed an application under Japanese Patent Application No. 100236/1983 on a method in which the above-mentioned problem has been solved, and when color-separating a laid-out original picture for a complete block copy with line picture regions such as characters and/or graphics mixed with picture pattern regions, the picture pattern regions and line picture regions are recorded in a single scanning step as color-separated halftone images and reproduced high-resolution line picture images faithful to the original respectively.